public class Demo4 {
    public static void main(String[] args) {
        Demo1 s1 =new Demo1();
        s1.setR(5);
        s1.setA(4);
        s1.setB(5);
        s1.yuan();
        s1.changfanxing();


        Demo1 s2 =new Demo1(5,4,5);
        s2.yuan();
        s2.changfanxing();
    }
}

